How many redundancy systems are installed on a 777?
A. As to the critical flight data displays, which the pilots and autopilot must have to navigate the plane safely, the ADIRU is the primary system, and the SAARU is the secondary backup redundancy system. Both systems access redundancy inputs, such as internal gyros, accelerometers, air data module inputs (center, right and left modules), 3 pitot tubes , 2 angle of attack vanes, and 3 static ports. There is also a: —-Standby attitude indicator, which displays SAARU attitude. —-Standby airspeed indicator, which displays airspeed calculated from two standby air data modules (one pitot and one static), and displays that information in both digital and pointer readout forms. —-Standby altimeter, which displays altitude from the standby (static) air data module, in both digital and pointer readout forms. —-Standby liquid magnetic “whiskey” compass, which all airplanes have. The B-777 also has many other essential redundancy systems, which are not relevant to this particular air data
